Large Scale Spatial-Temporal Structure of Low Frequency Variability in URUGUAY River Basin

The particularly behaviour of low frequency as consequence of particular behaviour of Uruguay river variability it is necessary to study in detail the spatial distribution of low frequency signals in the streamflows.

The target of this paper is to improve the knowledge about low frequency of variability decadal to century of runoff and precipitation in the Uruguay river basin. By using filtered series of monthly streamflows and rainfalls between 1914 and 1995 previously filtered by means a low-pass filter, with a five years cut-off frequency a spatial and temporal analysis of variability was made.

The results show that a high percentage of total variability is associated to periods longer than five years. The most significative bands correspond to cycles around ten and thirty years, probably as consequence of solar-climate relationships.